Transformer Chip

This application is a continuation of, and claims the benefit of priority from International Application No. PCT/JP2024/002553, filed on Jan. 29, 2024, which claims the benefit of priority from Japanese Patent Application No. 2023-018609, filed on Feb. 9, 2023, the entire contents of each of which are incorporated herein by reference.

The following description relates to a transformer chip.

An insulated gate driver is an example of a gate driver that applies gate voltage to a gate of a switching element, such as a transistor. Patent Literature 1 describes an example of an electronic component that includes a transformer chip having a primary-side coil and a secondary coil.

Throughout the drawings and the detailed description, the same reference numerals refer to the same elements. The drawings may not be to scale, and the relative size, proportions, and depiction of elements in the drawings may be exaggerated for clarity, illustration, and convenience.

This description provides a comprehensive understanding of the methods, apparatuses, and/or systems described. Modifications and equivalents of the methods, apparatuses, and/or systems described are apparent to one of ordinary skill in the art. Sequences of operations are exemplary, and may be changed as apparent to one of ordinary skill in the art, with the exception of operations necessarily occurring in a certain order. Descriptions of functions and constructions that are well known to one of ordinary skill in the art may be omitted.

Exemplary embodiments may have different forms, and are not limited to the examples described. However, the examples described are thorough and complete, and convey the full scope of the disclosure to one of ordinary skill in the art.

Some embodiments of a signal transmission device and a transformer chip according to the present disclosure will now be described with reference to the drawings. Elements in the drawings are illustrated for simplicity and clarity and have not necessarily been drawn to scale. To facilitate understanding, hatching lines may not be shown in the cross-sectional drawings. The accompanying drawings merely illustrate exemplary embodiments of the present disclosure and are not intended to limit the present disclosure. Terms such as “first”, “second”, or “third” in this disclosure are used to distinguish subjects and are not used for ordinal purposes.

This detailed description provides exemplary embodiments of methods, apparatuses, and/or systems in accordance with the present disclosure. Further, this detailed description is illustrative and is not intended to limit embodiments of the present disclosure or the application and use of the embodiments.

In this specification, the phrase “at least one of” as used in this disclosure means “one or more” of a desired choice. As one example, the phrase “at least one of” as used in this disclosure means “only one single choice” or “both of two choices” if the number of its choices is two. As another example, the phrase “at least one of” as used in this disclosure means “only one single choice” or “any combination of two or more choices” if the number of its choices is three or more.

The overall configuration of a signal transmission devicein accordance with an embodiment will now be described with reference to.

schematically shows the circuit configuration of the signal transmission devicein accordance with the embodiment.schematically shows an example of the internal configuration (planar structure) of the signal transmission device.schematically shows an example of part of the internal configuration (cross-sectional structure) of the signal transmission device. To simplify illustration,does not show hatching lines.

As shown in, the signal transmission devicemay be used in an inverter device. The inverter deviceincludes a control circuit (electronic control unit, ECU), the signal transmission device, and switching elementsand. The signal transmission deviceis used as a gate driver that drives the switching elementwith the control circuit.shows the signal transmission devicethat drives the switching element.

The switching elementis a high-side switching element connected to a drive power supply, for example. The switching elementis a low-side switching element. Examples of the switching elementsandinclude transistors, such as a Si metal-oxide-semiconductor field-effect transistor (Si MOSFET), a SiC MOSFET, an insulated gate bipolar transistor (IGBT), or the like.

The signal transmission deviceapplies a drive voltage signal to a control terminal of the switching element. In the example described hereinafter, the switching elementsandare SiC MOSFETs. The signal transmission deviceis provided for each of the switching elementsand, and the switching elementsandare driven separately.

The signal transmission deviceincludes a low-voltage circuitto which a first voltage Vis applied, a high-voltage circuitto which a second voltage Vthat is higher than the first voltage Vis applied, and a transformerdisposed between the low-voltage circuitand the high-voltage circuit. That is, the transformerconnects the low-voltage circuitand the high-voltage circuit. The first voltage Vand the second voltage Vare DC voltages.

The signal transmission deviceof the present embodiment is configured so that, in response to a control signal from the control circuit, the low-voltage circuittransmits a signal to the high-voltage circuitvia the transformer, and the high-voltage circuitoutputs a drive voltage signal.

The signal transmitted from the low-voltage circuittoward the high-voltage circuit, or the signal output from the low-voltage circuit, includes, for example, a signal for driving the switching element, such as a set signal (SET) and a reset signal (RESET). The set signal is a signal that transmits a rising edge of a control signal of the control circuit, and the reset signal is a signal that transmits a falling edge of the control signal of the control circuit. In other words, the set signal and the reset signal are signals for generating a drive voltage signal for the switching element. The set signal and the reset signal correspond to a first signal.

More specifically, the low-voltage circuitis configured to be actuated when the first voltage Vis applied to the low-voltage circuit. The low-voltage circuitis electrically connected to the control circuitand generates a set signal and a reset signal based on a control signal received from the control circuit. For example, the low-voltage circuitgenerates a set signal in response to a rising edge of the control signal, and generates a reset signal in response to a falling edge of the control signal. The low-voltage circuittransmits the generated set signal and reset signal toward the high-voltage circuit.

The high-voltage circuitis configured to be actuated when the second voltage Vis applied to the high-voltage circuit. The high-voltage circuitis electrically connected to a gate of the switching element. Based on the set signal and the reset signal received from the low-voltage circuit, the high-voltage circuitgenerates a drive voltage signal for driving the switching element, and applies the drive voltage signal to the gate of the switching element. In other words, the high-voltage circuitgenerates a drive voltage signal applied to the gate of the switching elementin response to the first signal output from the low-voltage circuit. More specifically, the high-voltage circuitgenerates a drive voltage signal for activating the switching elementbased on the set signal, and applies the drive voltage signal to the gate of the switching element. Further, the high-voltage circuitgenerates a drive voltage signal for deactivating the switching elementbased on the reset signal, and applies the drive voltage signal to the gate of the switching element. In this manner, the signal transmission devicecontrols activation and deactivation of the switching element.

The high-voltage circuitincludes, for example, an RS type flip-flop circuit, which receives a set signal and a reset signal, and a driver, which generates a drive voltage signal in response to an output signal of the RS type flip-flop circuit. The specific circuit configuration of the high-voltage circuitmay be changed.

In the signal transmission deviceof the present embodiment, the transformerinsulates the low-voltage circuitfrom the high-voltage circuit. More specifically, the transformerrestricts transmission of DC voltage between the low-voltage circuitand the high-voltage circuitwhile permitting transmission of various signals, such as the set signal and the reset signal.

Therefore, a state in which the low-voltage circuitand the high-voltage circuitare insulated from each other refers to a state in which transmission of DC voltage is restricted between the low-voltage circuitand the high-voltage circuitand transmission of a signal is permitted between the low-voltage circuitand the high-voltage circuit.

The signal transmission devicehas a dielectric breakdown voltage of, for example, 2500 Vrms or greater and 7500 Vrms or less. The dielectric breakdown voltage of the signal transmission deviceof the present embodiment is approximately 5000 Vrms. The dielectric breakdown voltage of the signal transmission deviceis not limited to any specific numerical value.

In the present embodiment, ground GNDof the low-voltage circuitand ground GNDof the high-voltage circuitare arranged independent from each other. Hereinafter, the potential of the ground GNDof the low-voltage circuitwill be referred to as the first reference potential, and the potential of the ground GNDof the high-voltage circuitwill be referred to as the second reference potential. In this case, the first voltage Vis a voltage from the first reference potential, and the second voltage Vis a voltage from the second reference potential. The first voltage Vis, for example, 4.5 V or greater and 5.5 V or less. The second voltage Vis, for example, 9 V or greater and 24 V or less.

The transformerswill now be described in detail.

The signal transmission deviceof the present embodiment includes two transformerscorresponding to two signals transmitted from the low-voltage circuittoward the high-voltage circuit. To facilitate understanding, one of the two transformerswill be referred to as the transformerA, and the other one of the two transformerswill be referred to as the transformerB. In an example, the transformerA transmits a set signal. The transformerB transmits a reset signal. In an example, the set signal and the reset signal may be for a reception circuit included in the high-voltage circuit.

The signal transmission deviceincludes a low-voltage signal lineA, which connects the low-voltage circuitto the transformerA, and a low-voltage signal lineB, which connects the low-voltage circuitto the transformerB. Accordingly, the low-voltage signal lineA transmits a set signal from the low-voltage circuitto the transformerA. The low-voltage signal lineB transmits a reset signal from the low-voltage circuitto the transformerB.

The signal transmission deviceincludes a high-voltage signal lineA, which connects the transformerA and the high-voltage circuit, and a high-voltage signal lineB, which connects the transformerB and the high-voltage circuit. Accordingly, the high-voltage signal lineA transmits a set signal from the transformerA to the high-voltage circuit. The high-voltage signal lineB transmits a reset signal from the transformerB to the high-voltage circuit.

The transformerA transmits a set signal from the low-voltage circuitto the high-voltage circuitwhile electrically insulating the low-voltage circuitfrom the high-voltage circuit. The transformerB transmits a reset signal from the low-voltage circuitto the high-voltage circuitwhile electrically insulating the low-voltage circuitfrom the high-voltage circuit.

The transformersA andB each include a first coiland a second coil. The first coiland the second coilare electrically insulated from each other and are configured to be magnetically coupled to each other.

The second coilof the transformerA is connected to the low-voltage circuitby the low-voltage signal lineA and to the ground GNDof the low-voltage circuit. More specifically, the second coilof the transformerA has a first end electrically connected to the low-voltage circuit, and a second end electrically connected to the ground GNDof the low-voltage circuit. The second coilof the transformerB is connected to the low-voltage circuitby the low-voltage signal lineB and to the ground GNDof the low-voltage circuit. More specifically, the second coilof the transformerB has a first end electrically connected to the low-voltage circuit, and a second end electrically connected to the ground GNDof the low-voltage circuit. In this manner, the potential at the second end of the second coilin each of the transformersA andB corresponds to the first reference potential. The first reference potential is, for example, 0 V.

The first coilof the transformerA is connected to the high-voltage circuitby the high-voltage signal lineA and to the ground GNDof the high-voltage circuit. More specifically, the first coilof the transformerA has a first end electrically connected to the high-voltage circuit, and a second end electrically connected to the ground GNDof the high-voltage circuit. The first coilof the transformerB is connected to the high-voltage circuitby the high-voltage signal lineB and to the ground GNDof the high-voltage circuit. More specifically, the first coilof the transformerB has a first end electrically connected to the high-voltage circuit, and a second end electrically connected to the ground GNDof the high-voltage circuit. In this manner, the potential at the second end of the first coilin each of the transformersA andB corresponds to the second reference potential. The ground GNDof the high-voltage circuitis connected to a source of the switching element. Accordingly, the second reference potential varies when the inverter deviceis driven and may become 600 V or greater, for example.

is an example of a plan view showing the internal configuration of the signal transmission device.is an example of a cross-sectional view showing the internal configuration of the signal transmission device. In, the circuit configuration of the signal transmission deviceis simplified. Thus, the number of external terminals of the signal transmission deviceinis greater than the number of external terminals of the signal transmission devicein. The number of external terminals of the signal transmission devicerefers to the number of external electrodes that allow for connection between the signal transmission deviceand an electronic component external to the signal transmission device, such as the control circuit, the switching element(refer to), or the like. Also, in the signal transmission deviceshown in, the number of signal lines (number of wires Wto W, described later) for transmitting a signal from the low-voltage circuitto the high-voltage circuitis greater than the number of signal lines in the signal transmission deviceshown in.

As shown in, the signal transmission deviceis a semiconductor device, in which multiple semiconductor chips are packaged, and is mounted on a circuit substrate of the inverter device, for example. The switching elementsandare mounted on another mount substrate that differs from the circuit substrate. The mount substrate is attached to a cooling device.

The package type of the signal transmission deviceis small outline (SO). In the present embodiment, the signal transmission deviceis a small outline package (SOP). For example, a low-voltage circuit chip, a high-voltage circuit chip, and a transformer chipare semiconductor chips. The low-voltage circuit chipis mounted on a low-voltage lead frame. The high-voltage circuit chipis mounted on a high-voltage lead frame. The chips,, andand part of the lead framesandare encapsulated by a mold resin. In the present embodiment, the transformer chipand the mold resincorrespond to an insulation module that insulates the low-voltage circuitfrom the high-voltage circuit. In, the mold resinis indicated by double-dashed lines such that the internal structure of the signal transmission devicecan be shown. The package type of the signal transmission devicemay be changed.

The mold resinis formed from an electrically insulative material. An example of such resin includes a black epoxy resin. The mold resinhas the shape of a rectangular plate having a thickness-wise direction that is parallel to the z-direction. The mold resinincludes four resin side surfacesto. More specifically, the mold resinincludes the resin side surfacesandserving as two end surfaces in the x-direction, and the resin side surfacesandserving as two end surfaces in the y-direction. The x-direction and the y-direction are orthogonal to the z-direction. The x-direction and the y-direction are orthogonal to each other. The x-direction corresponds to a first direction. The y-direction corresponds to a second direction. In the description hereafter, a plan view means a view taken in the z-direction.

The low-voltage lead frameand the high-voltage lead frameare conductors. In the present embodiment, the low-voltage lead frameand the high-voltage lead frameare formed from a material containing copper (Cu), iron (Fe), or the like. The lead framesandextend from the inside to the outside of the mold resin.

The low-voltage lead frameincludes a low-voltage die padarranged in the mold resin, and low-voltage leadsextending from the inside to the outside of the mold resin. The low-voltage leadsform the external terminals for electrical connection with an external electronic device, such as the control circuit(refer to).

In the present embodiment, both the low-voltage circuit chipand the transformer chipare mounted on the low-voltage die pad. In plan view, the low-voltage die padis arranged so that its central part in the y-direction is located closer to the resin side surfacethan the central part of the mold resinis in the y-direction. In the present embodiment, the low-voltage die padis not exposed from the mold resin. In plan view, the low-voltage die padhas a rectangular shape, in which long sides extend in the x-direction and short sides extend in the y-direction.

The low-voltage leadsare spaced apart from one another in the x-direction. The two outermost low-voltage leadsin the x-direction are integrated with the low-voltage die pad. Each of the low-voltage leadspartially projects out of the mold resinfrom the resin side surface.

The high-voltage lead frameincludes a high-voltage die padarranged in the mold resin, and high-voltage leadsextending from the inside to the outside of the mold resin. The high-voltage leadsform the external terminals for electrical connection with an external electronic device, such as the gate of the switching element(refer to).

The high-voltage circuit chipis mounted on the high-voltage die pad. In plan view, the high-voltage die padis located closer to the resin side surfacethan the low-voltage die padis in the y-direction. In the present embodiment, the high-voltage die padis not exposed from the mold resin. In plan view, the high-voltage die padhas a rectangular shape, in which long sides extend in the x-direction and short sides extend in the y-direction.

The low-voltage die padand the high-voltage die padare spaced apart from each other in the y-direction. Accordingly, the y-direction may also be referred to as the arrangement direction of the two die padsand.

The dimensions of the low-voltage die padand the high-voltage die padin the y-direction are determined in accordance with the size and quantity of the mounted semiconductor chips. In the present embodiment, the low-voltage circuit chipand the transformer chipare mounted on the low-voltage die pad, and the high-voltage circuit chipis mounted on the high-voltage die pad. Accordingly, the low-voltage die padis larger than the high-voltage die padin the y-direction.

The high-voltage leadsare spaced apart from one another in the x-direction. Two of the high-voltage leadsare integrated with the high-voltage die pad. Each of the high-voltage leadspartially projects out of the mold resinfrom the resin side surface.

In the present embodiment, the number of high-voltage leadsis the same as the number of low-voltage leads. As apparent from, the low-voltage leadsand the high-voltage leadsare arranged next to one another in a direction (x-direction) orthogonal to the arrangement direction (y-direction) of the low-voltage die padand the high-voltage die pad. The number of high-voltage leadsand the number of low-voltage leadsmay be changed.

In the present embodiment, the low-voltage die padis supported by the two low-voltage leadsintegrated with the low-voltage die pad. The high-voltage die padis supported by the two high-voltage leadsintegrated with the high-voltage die pad. Accordingly, the die padsanddo not include suspension leads exposed from the resin side surfacesand. This allows the low-voltage lead frameand the high-voltage lead frameto be spaced apart by a relatively long insulating distance.

The low-voltage circuit chip, the high-voltage circuit chip, and the transformer chipare spaced apart from one another in the y-direction. The low-voltage circuit chip, the transformer chip, and the high-voltage circuit chipare arranged in this order from the low-voltage leadsto the high-voltage leadsin the y-direction.

The low-voltage circuit chipincludes the low-voltage circuitshown in. In plan view, the low-voltage circuit chiphas a rectangular shape with short sides and long sides. In plan view, the low-voltage circuit chipis mounted on the low-voltage die padsuch that the long sides extend in the x-direction and the short sides extend in the y-direction. As shown in, the low-voltage circuit chiphas a chip main surfaceand a chip back surfaceat opposite sides in the z-direction. The chip back surfaceof the low-voltage circuit chipis bonded to the low-voltage die padby a conductive bonding material SD. The conductive bonding material SD is solder, silver (Ag) paste, or the like.

First electrode pads, second electrode pads, and third electrode padsare formed on the chip main surfaceof the low-voltage circuit chip. The electrode padstoare electrically connected to the low-voltage circuit.